Análisis de cambios en los afloramientos en el Pacífico ecuatorial este, durante eventos El Niño Oscilación del Sur

The ocean reanalysis Simple Ocean Data Assimilation (SODA) 2.2.4 is used to explore the changes in upwelling from normal conditions to either El Niño or La Niña conditions. Physical and thermodynamic variables from the reanalysis are used to explore the structure and behaviour of El Niño Southern Oscillation (ENSO) events. The results of this analysis show that sea surface temperature (SST), entrainment velocity, wind stress, mixed layer depth, wind stress curl, and heat content anomalies are in general agreement with ENSO theory. Interestingly, the distribution of upwelling based on the entrainment velocity is very patchy, which led us to explore zonal and meridional sections of vertical velocity. We used three methods to compute changes in upwelling during ENSO events. The first method computes upwelling within the áreas of SST anomalies during ENSO events. During El Niño events upwelling shows prominent decadal variability, while during La Niña the decadal variability is weaker. A new upwelling index is used for the second method, and upwelling is computed in the áreas of strong upwelling anomalies. The variability of upwelling is higher in periods of reduced upwelling than in periods of strong upwelling. Despite the fact that the new index is computed independently, it agrees in the timing of the index used to define ENSO events for this research. The first and second methods show that the amplitude of SST anomalies and upwelling anomalies do not have a direct relationship, suggesting that upwelling does not explain all of the variance in SST. The last method used is to compute changes in upwelling in the Niño 1+2 region during ENSO events. In the east Pacific there is almost no correlation between upwelling and SST anomalies during ENSO, but this might be attributed to the fact that the Niño 1+2 region is a relatively small region compared to the Niño 3.4 region that is used to define ENSO events. In general, the time series of SST and upwelling anomalies agree well just in the cases when ENSO events are prominently in the eastern Pacific.

Bibliographic Details

Main Author:	Perugachi Salamea, C.
Format:	Journal Contribution biblioteca
Language:	Spanish / Castilian
Published:	2013
Subjects:	Upwelling, El Nino phenomena, Surface temperature, Thermodynamics,
Online Access:	http://hdl.handle.net/1834/5754
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